In this Wednesday, Nov. 6, 2019, photo, Border Patrol agents chase two men thought to have entered the country illegally, near McAllen, Texas, along the U.S.-Mexico border. In the Rio Grande Valley, the southernmost point of Texas and historically the busiest section for border crossings, the U.S. Border Patrol is apprehending around 300 people daily, down from as many as 2,000 people a day in May. (AP Photo/Eric Gay)

EL PASO, Texas (Border Report) — Assaults on Border Patrol agents are up 400% in the Big Bend Sector of Texas, as more adult males — some of them with a violent past — are trying to enter the U.S. illegally, the federal agency said.

“Last year we were going after family units and unaccompanied minors, so we had very low incidents of violence,” said Chief Agent Matthew Hudak. “But now, some of these single adult males have a prior criminal history or have come here before and have a lifetime ban on reentry, so they’re trying to avoid arrest.”

Five assaults against agents remain under investigation this fiscal year, with the perpetrators facing felony federal charges in addition to sanctions for illegal entry, he said. Only one such incident was reported during the same period the previous fiscal year.

The spike reflects shifting demographics of migrants apprehended at the Southwest border, as Trump administration policies take away the incentives for Central American families to come, federal officials say.

In this Feb. 5, 2019, file photo, Border Patrol agent Vincent Pirro looks on near a border wall that separates the cities of Tijuana, Mexico, and San Diego, in San Diego. Migrant apprehensions along the Southwest border were down 28 percent for June compared to May. (AP Photo/Gregory Bull, File)

The Trump administration maintains that allowing asylum-seeking migrant families to enter the country and be released while their petition is evaluated creates a draw for many others to come. His administration has applied a policy called Migrant Protection Protocols (MPP) that makes the families wait in Mexico and worked out a deal to send others to Guatemala. Both policies are being challenged in court, with MPP scheduled to end this week in Arizona and California, per orders of the 9th U.S. Circuit Court.

Last May, 72% of migrant apprehensions were either family units or unaccompanied minors; last month, three out of four apprehensions were single adults, most of them from Mexico. That’s a 73% drop in family units and minors traveling by themselves, the Border Patrol said.

In the Big Bend Sector of Texas, which includes 157 miles of border, overall apprehensions are down 33% this past February compared to February 2019. Only 17% of those taken into custody since October have been families or minors traveling by themselves. The rest were adult males, mostly from Mexico, followed by Central Americans, Ecuadorians and Cubans.

“(Single adults) is the demographic that tries to evade arrest, avoid detection and tends to move to more remote areas. It’s not the groups that walk up and turn themselves into agents. There’s a lot of tracking and pursuit involved,” Hudak said in explaining why agents are now at higher risk of assault.

On the other hand, with fewer families and unaccompanied children in particular, and fewer migrants, in general, coming to the U.S. border for the first time, the Border Patrol has been able to increase drug seizures. Arrests involving people carrying loads of marijuana are up 10% this fiscal year, meth seizures are up 7% and heroin seizures 1,000% in the sector.

“That’s reflective of the fact that agents are able to get out into the field more and go after this traffic whereas we didn’t have that opportunity last year because of the high volumes of arrests,” Hudak said.